Plant biology

New Plant Immune Pathway

Science's STKE  23 Jul 2002:
Vol. 2002, Issue 142, pp. tw269-TW269
DOI: 10.1126/stke.2002.142.tw269

The plant gene NIM1 encodes a protein with similarity to members of the IκB family of proteins, which are transcriptional regulators that function in mammalian immune system. Plants with mutations in NIM1 are unresponsive to salicylic acid signaling, which is required for the systemic acquired resistance (SAR) response to pathogens. To search for new regulators of plant immune responses, Kim and Delaney screened for genetic suppressor mutations in Arabidopsis that relieved susceptibility to pathogens in nim1-1 mutants. The suppressor of nim1-1 (son1) mutant they isolated revealed a previously uncharacterized defense pathway independent of the SAR response. Resistance was restored in son1 mutants without activation of the pathogenesis-related genes normally regulated during SAR. The Son-1 gene was found to encode a protein with an NH2-terminal F-box characteristic of proteins that target specific proteins to E3 ubiquitin ligase complexes for subsequent destruction. The SON1 protein thus appears to be a negative regulator of a plant defense response that may target other proteins for destruction in the ubiquitin-proteasome pathway.

H. S. Kim, T. P Delaney, Arabidopsis SON1 Is an F-Box Protein That Regulates a Novel Induced Defense Response Independent of Both Salicylic Acid and Systemic Acquired Resistance. Plant Cell 14, 1469-1482 (2002). [Abstract] [Full Text]